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Production of cellobionate from cellulose using an engineered Neurospora crassa strain with laccase and redox mediator addition.

Hildebrand A, Kasuga T, Fan Z - PLoS ONE (2015)

Bottom Line: By adding low concentrations of laccase and a redox mediator to the fermentation, CDH can be efficiently oxidized by the redox mediator, with in-situ re-oxidation of the redox mediator by laccase.The conversion of cellulose to cellobionate was optimized by evaluating pH, buffer, and laccase and redox mediator addition time on the yield of cellobionate.This paper describes a working concept of cellobionate production from cellulose using the CDH-ATBS-laccase system in a fermentation system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Avenue, Davis, CA, 95616, United States of America.

ABSTRACT
We report a novel production process for cellobionic acid from cellulose using an engineered fungal strain with the exogenous addition of laccase and a redox mediator. A previously engineered strain of Neurospora crassa (F5∆ace-1∆cre-1∆ndvB) was shown to produce cellobionate directly from cellulose without the addition of exogenous cellulases. Specifically, N. crassa produces cellulases, which hydrolyze cellulose to cellobiose, and cellobiose dehydrogenase (CDH), which oxidizes cellobiose to cellobionate. However, the conversion of cellobiose to cellobionate is limited by the slow re-oxidation of CDH by molecular oxygen. By adding low concentrations of laccase and a redox mediator to the fermentation, CDH can be efficiently oxidized by the redox mediator, with in-situ re-oxidation of the redox mediator by laccase. The conversion of cellulose to cellobionate was optimized by evaluating pH, buffer, and laccase and redox mediator addition time on the yield of cellobionate. Mass and material balances were performed, and the use of the native N. crassa laccase in such a conversion system was evaluated against the exogenous Pleurotus ostreatus laccase. This paper describes a working concept of cellobionate production from cellulose using the CDH-ATBS-laccase system in a fermentation system.

No MeSH data available.


Related in: MedlinePlus

Optimization of laccase (0.05 U/mL) and ABTS (0.01 mM) addition time with the F5Δace-1Δcre-1ΔndvB strain grown in 1x Vogel’s medium and 20 g/L Avicel.The values shown are the means of biological triplicates with the error bars representing the standard deviations.
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pone.0123006.g004: Optimization of laccase (0.05 U/mL) and ABTS (0.01 mM) addition time with the F5Δace-1Δcre-1ΔndvB strain grown in 1x Vogel’s medium and 20 g/L Avicel.The values shown are the means of biological triplicates with the error bars representing the standard deviations.

Mentions: The addition of laccase and ABTS to the fermentation system employing the F5Δace-1Δcre-1ΔndvB strain on 20g/L Avicel was optimized. 0.05 U/mL of laccase and 0.01 mM ABTS were added at various time points. As shown in Fig 4, the cellobiose is completely converted to CBA within 48 hours for all addition times, with an optimal addition time at 120 hours into the fermentation. The maximum CBA concentration occurs at 168 hours with a slight decrease after that for all cases. When no laccase and ABTS are added, maximum cellobiose concentration also occurs 168 hours into the fermentation, and cellobionate production reaches a plateau at that time point as well.


Production of cellobionate from cellulose using an engineered Neurospora crassa strain with laccase and redox mediator addition.

Hildebrand A, Kasuga T, Fan Z - PLoS ONE (2015)

Optimization of laccase (0.05 U/mL) and ABTS (0.01 mM) addition time with the F5Δace-1Δcre-1ΔndvB strain grown in 1x Vogel’s medium and 20 g/L Avicel.The values shown are the means of biological triplicates with the error bars representing the standard deviations.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388835&req=5

pone.0123006.g004: Optimization of laccase (0.05 U/mL) and ABTS (0.01 mM) addition time with the F5Δace-1Δcre-1ΔndvB strain grown in 1x Vogel’s medium and 20 g/L Avicel.The values shown are the means of biological triplicates with the error bars representing the standard deviations.
Mentions: The addition of laccase and ABTS to the fermentation system employing the F5Δace-1Δcre-1ΔndvB strain on 20g/L Avicel was optimized. 0.05 U/mL of laccase and 0.01 mM ABTS were added at various time points. As shown in Fig 4, the cellobiose is completely converted to CBA within 48 hours for all addition times, with an optimal addition time at 120 hours into the fermentation. The maximum CBA concentration occurs at 168 hours with a slight decrease after that for all cases. When no laccase and ABTS are added, maximum cellobiose concentration also occurs 168 hours into the fermentation, and cellobionate production reaches a plateau at that time point as well.

Bottom Line: By adding low concentrations of laccase and a redox mediator to the fermentation, CDH can be efficiently oxidized by the redox mediator, with in-situ re-oxidation of the redox mediator by laccase.The conversion of cellulose to cellobionate was optimized by evaluating pH, buffer, and laccase and redox mediator addition time on the yield of cellobionate.This paper describes a working concept of cellobionate production from cellulose using the CDH-ATBS-laccase system in a fermentation system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Avenue, Davis, CA, 95616, United States of America.

ABSTRACT
We report a novel production process for cellobionic acid from cellulose using an engineered fungal strain with the exogenous addition of laccase and a redox mediator. A previously engineered strain of Neurospora crassa (F5∆ace-1∆cre-1∆ndvB) was shown to produce cellobionate directly from cellulose without the addition of exogenous cellulases. Specifically, N. crassa produces cellulases, which hydrolyze cellulose to cellobiose, and cellobiose dehydrogenase (CDH), which oxidizes cellobiose to cellobionate. However, the conversion of cellobiose to cellobionate is limited by the slow re-oxidation of CDH by molecular oxygen. By adding low concentrations of laccase and a redox mediator to the fermentation, CDH can be efficiently oxidized by the redox mediator, with in-situ re-oxidation of the redox mediator by laccase. The conversion of cellulose to cellobionate was optimized by evaluating pH, buffer, and laccase and redox mediator addition time on the yield of cellobionate. Mass and material balances were performed, and the use of the native N. crassa laccase in such a conversion system was evaluated against the exogenous Pleurotus ostreatus laccase. This paper describes a working concept of cellobionate production from cellulose using the CDH-ATBS-laccase system in a fermentation system.

No MeSH data available.


Related in: MedlinePlus